An alkaline earth metal hydride such as magnesium hydride is expected to act as a hydrogen storage system which is reversible between the metal hydride and metal, and various production methods thereof have been reported. For example, a method for hydrogenating particulate magnesium with a magnesium catalyst in a fine particle form having high reactivity (Patent Literature 1), a method for hydrogenating magnesium by removing the surface coating of raw material powder while maintaining a temperature at a specific level (Patent Literature 2), and a method including going through a compressed material obtained by accumulating and compressing a plurality of magnesium flakes (Patent Literature 3) have been reported.